The fields of sexual health and sexual pleasure are entwining as the adult novelty business continues to grow. The global sexual wellness market, which includes everything from condoms and lingerie to sex toys, is currently worth around $16 billion and expected to reach $21 billion by 2019, according to research firm Technavio.

Now, manufacturers are looking beyond simple stimulation devices; wearables are gaining traction, though they're a bit different than the wristbands so many people associate with wearable tech.

OhMiBod's Krush, due out this spring at a price of $75, is a device women can insert vaginally to help strengthen their pelvic muscles. And as a "reward" of sorts for completing exercises, the system has vibration patterns that allow it to also be used as a pleasure device.

"It's the gamification of sexual health," said Brian Dunham, co-founder of OhMiBod. His company is a leader in the wearable sexual product field. Its OhMiBod Remote, a vibrator worn in a user's clothing and controlled remotely by other people, was one of the first products to explore the space.

Nuelle's Fiera is a different sort of sex wearable, designed to help women focus on arousal and boost their libido. The $250 hands-free device is targeted at women who mentally desire to have sex with their partner but have trouble getting their bodies to respond accordingly.

"The idea is you wear this for five to 15 minutes before you want to have sex," said Nuelle founder Karen Long. "It's not just for fun, it's a part of life."

Other sex wearables are in development, including SexFit, a Bluetooth- and Wi-Fi-equipped device that helps men achieve and maintain erections and tracks their sexual performance using a device akin to a pedometer.

And for the past several years there have been wearable sex toys that allow couples who are separated by distance to stimulate each other — such as the We-Vibe 4 Plus or Durex's Fundawear experiment.

While there's certainly a push by some adult novelty makers in this direction, the jury is still out on whether wearables are, in fact, the next big thing in sex toys. Steven Hirsch of film studio Vivid and a longtime veteran of the adult industry, remains a bit skeptical.

"My feeling is it's probably a small market," he said. "People always get excited about new technology and Internet-connected devices — and I do think there's a market for it — but I don't think it's the primary market."

But Chauntelle Tibbals, a former visiting scholar at the University of Southern California and author of "Exposure: A Sociologist Explores Sex, Society and Adult Entertainment," says sex wearables are a logical extension for the adult novelty industry.

"It makes sense in this world where everybody has a Fitbit or an app to track their exercise that they'd track their sexual activity, too," she said.